Dendritic cells migrate from the skin to the draining lymph nodes. They transport immunogenic MHC-peptide complexes, present them to Ag-specific T cells in the T areas, and thus generate immunity. Migrating dendritic cells encounter physical obstacles, such as basement membranes and collagen meshwork. Prior work has revealed that matrix metalloproteinase-9 (MMP-9) contributes to mouse Langerhans cell migration. In this study, we use mouse and human skin explant culture models to further study the role of MMPs in the migration and maturation of skin dendritic cells. We found that MMP-2 and MMP-9 are expressed on the surface of dendritic cells from the skin, but not from other sources. They are also expressed in migrating Langerhans cells in situ. The migration of both Langerhans cells and dermal dendritic cells is inhibited by a broad spectrum inhibitor of MMPs (BB-3103), by Abs to MMP-9 and -2, and by the natural tissue inhibitors of metalloproteinases (TIMP), TIMP-1 and TIMP-2. Inhibition by anti-MMP-2 and TIMP-2 define a functional role for MMP-2 in addition to the previously described function of MMP-9. The importance of MMP-9 was emphasized using MMP-9-deficient mice in which Langerhans cell migration from skin explants was strikingly reduced. However, MMP-9 was only required for Langerhans cell migration and not maturation, since nonmigrating Langerhans cells isolated from the epidermis matured normally with regard to morphology, phenotype, and T cell stimulatory function. These data underscore the importance of MMPs, and they may be of relevance for therapeutically regulating dendritic cell migration in clinical vaccination approaches.

Ty virus-like particles consist of a single protein species that can be produced in yeast. Recombinant Ty-VLPs carrying a string of up to 15 defined cytotoxic T lymphocyte (CTL) epitopes from Plasmodium species prime protective CTL responses in mice following a single administration without adjuvant. Effective processing of epitopes from the string was demonstrated in vitro and in vivo and was not affected by flanking sequences.

Previous reports have indicated that both dendritic cells and macrophages have the ability to induce cytotoxic T lymphocyte (CTL) and T helper (Th) cell responses in vivo. Dendritic cells process exogenous antigens conventionally for presentation on major histocompatibility complex (MHC) class II molecules. However, unconventional processing of exogenous antigens in vitro for presentation on MHC class I molecules is still an open question. In this study, we report that a cloned dendritic cell line (D2SC/1) is able to present cell debris-associated exogenous viral proteins to MHC class I-restricted CTL in vitro. The dendritic cell line was very efficient in processing recombinant lymphocytic choriomeningitis virus nucleoprotein (LCMV NP) and presenting the class I-restricted epitope to CTL primed in vivo. Peritoneal macrophages could also process the recombinant LCMV NP for subsequent MHC class I presentation, but were less efficient compared to the dendritic cells. Furthermore, recombinant yeast-derived virus-like particles carrying the HIV-1 V3 loop (V3-VLP), which are protenaceous and do not contain any lipid, were also found to be efficiently processed by the dendritic cell line for presentation of the class I-restricted epitope. These results clearly indicate that viral proteins, in particulate form or associated with cell debris, are processed by dendritic cells for CTL induction.

A simple skin wash technique suitable for the quantitative and functional analysis of biomolecules in AD is described. Using this method we show that MMPs, and in particular MMP-8 and MMP-9, represent an important potential component of the pathology of AD. The method is expected to prove useful in advancing our understanding of AD and in identifying biomarkers for the evaluation of new therapies.

The desirability of inducing cytotoxic T cell responses to defined epitopes in humans has led to the development of a variety of recombinant delivery systems. Recombinant protein particles derived from a yeast retrotransposon (Ty) and the modified Ankara vaccinia (MVA) virus can deliver large epitope strings or even whole proteins. Both have previously been administered safely in humans. Immunization with recombinant Ty and MVA containing a single Plasmodium berghei class I-binding epitope provided 95 % sterile protection against malaria in mice. The sequence of immunization, Ty followed by MVA, was critical to elicit high levels of IFN-+ -producing cells and protection. The reciprocal sequence (MVA/TY) or homologous boosting was not protective. Both constructs (Ty and MVA) contain the H-2K d -restricted pb9 CTL epitope from the circumsporozoite protein of P. berghei among a string of 8-15 human P. falciparum-derived CTL epitopes restricted through 7 common HLA alleles as well as widely recognized CD4 T cell epitopes. Thus, the novel recombinant Ty/MVA prime/boost combination with these constructs provides a safe alternative for evaluation for human vaccination against P. falciparum malaria.